1. Field of the Invention
The present invention relates to a heater control unit, of an air conditioner equipped in an automobile, installed on an instrument panel to serve as a means for changing air amount and adjusting the temperature inside the automobile.
2. Description of the Related Arts
In a conventional heater control unit, a dial is rotated to change air amount and adjust the temperature inside the automobile. In the heater control unit of this type, a first bevel gear is mounted on a shaft with which the dial is connected, and the rotation of a second bevel gear engaging the first bevel gear is transmitted to a pivotal lever with which a cable extending from a damper of an air conditioner is connected. In this construction, the lever is pivoted by rotating the dial. As a result, the damper is opened and closed.
FIGS. 6 and 7 show how a shaft is mounted to a first conventional heater control unit. The heater control unit comprises a base member 1, and a shaft 2, one end of which is connected with a dial 3. The shaft 2 is held by a pair of supports la and lb which are integrally formed with the base member 1. A first bevel gear 4 is mounted on the shaft 2 at a position intermediate between the supports 1a and 1b. A portion 2a of the shaft 2 to be inserted into the first bevel gear 4 and a corresponding opening 4a of the first bevel gear 4 are sectionally rectangular as shown in FIG. 7 so that the first bevel gear 4 rotates together with the shaft 2.
A transmitting member 5 is rotatably supported by a pin 1c extending vertically upward from the base member 1. The transmitting member 5 comprises a second bevel gear 5a engaging the first bevel gear 4 and a spur gear 5b formed integrally with the second bevel gear 5a. Another spur gear engaging the spur gear 5b and a pivotal lever are fixed to a shaft which is supported on the base member 1, and the pivotal lever is connected to a damper of an air conditioner via a cable (not shown).
A construction for mounting a shaft to a second conventional heater control unit is described below with reference to FIGS. 8 and 9. A first bevel gear 12a is integrally formed with a shaft 12 to which a dial 13 is fixed. One end of the shaft 12 is supported by a first support 11a which is integrally formed with a base 11. The other end (distal end) of the shaft 12 is held in the following manner. That is, a second bevel gear 14 is supported on a pin 11b formed on the base 11, a support member 15 as a second support is mounted on a distal end 12b of the shaft 12, and the support 15 is fixed by a pin 16. The rotation of the second bevel gear 14 is transmitted to a pivotal lever via a spur gear not shown.
In the first conventional heater control unit, the distal end of the shaft 2 is inserted through the support 1a from the left side in FIG. 6 (instrument panel side), and then, the first bevel gear 4 is mounted on the shaft 2. Then, the distal end of the shaft 2 is inserted through the second support 1b, and then, a snap ring 6 is fitted to the shaft 2. Therefore, complicated works are required in the assembling operation. In the second conventional heater control unit, first bevel gear 12a is integral with the shaft 12, so that the operation of mounting the former on the latter is not required. But it is necessary to perform a complicated work of receiving the distal end of the shaft 12 by the holding member 15.
In the above-described conventional heater control units, not only complicated works are required in the assembling operation, but also the manufacturing cost is relatively high because it is difficult to integrate both the shaft and the first bevel gear with each other and the base member and the first and second supports with each other.